Tillage, Cropping Systems, and Nitrogen Fertilizer Source Effects on Soil Carbon Sequestration and Fractions

• Published in: Journal of environmental quality 2008-05, Vol.37 (3), p.880-888
• Main Authors: Sainju, U.M, Senwo, Z.N, Nyakatawa, E.Z, Tazisong, I.A, Chandra Reddy, K
• Format: Article
• Language: English
• Subjects: Agricultural practices; Agricultural wastes; ammonium nitrate; Biomass; Carbon; Carbon - chemistry; Carbon sequestration; conventional tillage; corn; cotton; Cover crops; crop residues; Cropping systems; Crops, Agricultural; fallow; Fertilizers; Gossypium; Gossypium hirsutum; Litter; microbial activity; microbial biomass; Mineralization; mulching; Nitrogen - chemistry; nitrogen fertilizers; no-tillage; Organic matter; Poultry; poultry manure; Productivity; rye; Secale; Secale cereale; silt loam soils; Soil conservation; soil microorganisms; soil organic carbon; Soil quality; Soils; Tillage; Zea mays
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2007.0241

Quantification of soil carbon (C) cycling as influenced by management practices is needed for C sequestration and soil quality improvement. We evaluated the 10-yr effects of tillage, cropping system, and N source on crop residue and soil C fractions at 0- to 20-cm depth in Decatur silt loam (clayey, kaolinitic, thermic, Typic Paleudults) in northern Alabama, USA. Treatments were incomplete factorial combinations of three tillage practices (no-till [NT], mulch till [MT], and conventional till [CT]), two cropping systems (cotton [Gossypium hirsutum L.]-cotton-corn [Zea mays L.] and rye [Secale cereale L.]/cotton-rye/cotton-corn), and two N fertilization sources and rates (0 and 100 kg N ha-1 from NH4NO3 and 100 and 200 kg N ha-1 from poultry litter). Carbon fractions were soil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), and potential C mineralization (PCM). Crop residue varied among treatments and years and total residue from 1997 to 2005 was greater in rye/cotton-rye/cotton-corn than in cotton-cotton-corn and greater with NH4NO3 than with poultry litter at 100 kg N ha-1. The SOC content at 0 to 20 cm after 10 yr was greater with poultry litter than with NH4NO3 in NT and CT, resulting in a C sequestration rate of 510 kg C ha-1 yr-1 with poultry litter compared with -120 to 147 kg C ha-1 yr-1 with NH4NO3. Poultry litter also increased PCM and MBC compared with NH4NO3. Cropping increased SOC, POC, and PCM compared with fallow in NT. Long-term poultry litter application or continuous cropping increased soil C storage and microbial biomass and activity compared with inorganic N fertilization or fallow, indicating that these management practices can sequester C, offset atmospheric CO2 levels, and improve soil and environmental quality.